Titan’s drones, which resemble solar-powered airplanes, are designed to fly as high as 65,000 feet and stay aloft for as long as five years — essentially functioning like cheap satellites. They could blanket large areas with wireless Internet signals, although the signals would be slower and unable to handle as much data as land-based Internet connections. For remote places like rural Africa, they would be enough to provide at least rudimentary access to the Internet through mobile phones.

Facebook would have to overcome lots of technical and legal problems before a global Facenet would be a reality. But the idea would allow the social network to one-up its rival, Google, which has its own far-fetched plan to extend the Internet to far-flung places via a network of balloons.

And it is a lot closer to reality than Amazon’s idea of drones that will deliver packages.